A colloidosome is defined as a microcapsule whose shell is formed by colloidal particles (with particle sizes usually less than 1 μm), which are adsorbed on the encapsulated substance and subsequently stabilized forming a shell by its cross-linking, fusion or sintering (Rossier, 2009).
The first report of colloidosomes-type microcapsules elaboration corresponds to the Velev and cols (1996) work, which used latex particles to stabilize and form 1-octanol colloidosomes. The method called soft template (soft template, (Rossier-Miranda et al., 2009)), uses the emulsion droplets as the base on which the colloidal solid particles forming the shell are adsorbed generating greater control and adsorption efficiency. In the method called hard template (hard template) solid particles are used as the colloidosome template.
Dismore and cols (2002) made colloidosomes without pretreatment, using polymethylmethacrylate (PMMA) particles immersed in a continuous organic phase of decahydronaphthalene in the drops of water presence. This method allows controlling the temperature and the heating time to adjust the porosity and strength of the shell, achieving versatility in the release kinetics of the encapsulated compounds. However, the high vitreous transition temperature of PMMA (92-142° C.) limits its use in thermolabile systems.
Guillot (2009) and Fujiwara (2010) reported colloidosomes made from clay minerals (v.g. montmorilonite and Laponite) and sodium silicate in ammonium acid carbonate (NH4HCO3) presence, using a W/O/W double emulsion as template. The proposed procedures, although successful in the colloidosome-type particles formation, are very difficult to scale at the industrial level and are more profiled for academic applications that allow the study and characterization of structured systems at microscopic level.
Liu and cols (2010) reported the production of hollow colloidosomes using nanosheets of Mg/Al double hydroxide in layers (LDH for its acronym in English). The interface structure allowed to be modulated depending on the type of organic solvent used for the emulsified oil phase extraction. Even though this modulation type of the interface structure of the colloidosome-type microcapsule is a great prospect for food applications, the use of organic solvents and the long times required for the adsorption processes, make non-viable its scaling at an industrial level.
The document WO 2009091255 discloses a process where colloidal particles of triglycerides, monoglycerides or diglycerides, proteins and cells are used as emulsion stabilizers and proteins and/or polysaccharides to fix the shell by a coacervation process. The main disadvantage of this process is the mono, di and triglycerides use, which, when melted, destabilize the colloidosome shell.
Wang and cols (2012) elaborated CaCO3 colloidosomes by sunflower oil emulsions generation and subsequent fixation of the solid particles in the shell, by CaCO3 crystals coprecipitation by reacting CaCl2) with CO2 in-situ. The colloidosomes generated with this methodology showed high resistance to the system water evaporation, as well as delaying the flavors release. While this process is feasible to be scaled at the industrial level, high concentrations of NaCl as a byproduct are generated, which must be eliminated by an additional washing step.
The document WO2009/037482 discloses the colloidosome-type microcapsules elaboration, using sterically stabilized polymer particles in the emulsions elaboration with the subsequent formation of the shell by increasing the system temperature at a temperature higher than the polymer vitreous transition. In this process a lower particles adsorption is generated on the interface with the consequent instability of the system when drying.
The patent WO2009/148598 describes the microfluidization technology use for the stabilized drops elaboration with polymeric, colloidal or lipid particles with potential use as an encapsulating medium for interest substances. The main drawback of this process is the use of polymer particles that necessarily require heat treatment for its sintering and forming a stable shell.
Obviously, the prior art shows the need to develop and optimize processes for obtaining colidosomes-type microcapsules from materials with application in the food industry, in the cosmetics field or in the pharmaceutical area.